Data Transmission Method and Apparatus in WLAN

ABSTRACT

A method for indicating a transmission opportunity (TXOP) duration in a wireless communication system includes generating, by a TXOP holder, a physical layer protocol data unit (PPDU). The PPDU includes a High Efficiency Signal field A (HE-SIGA), and the HE-SIGA includes a TXOP duration field. The TXOP duration field is used to indicate to other stations a remaining time for using a channel by a station. The TXOP duration field includes a first part which indicates a granularity used, and a second part which indicates the TXOP duration using the granularity indicated by the first part. The TXOP holder sends the generated PPDU.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International ApplicationNo.PCT/CN2017/071258, filed on Jan. 16, 2017, which claims priority toU.S. Provisional Application No. 62/278,437, filed on Jan. 14, 2016, andpriority to U.S. Provisional Application No. 62/363,344, filed on Jul.18, 2016. All of the afore-mentioned patent applications are herebyincorporated by reference in their entireties.

DEFINITION OF ABBREVIATIONS

HE: high efficiency

HE-SIGA: High Efficiency Signal field A

SU: single user

MU: multiple user

PPDU: physical layer protocol data unit

PHY: physical layer

MAC: medium access control layer

EDCA: enhanced distributed channel access

QoS: quality of service

SR: spatial reuse

DL: downlink

UL: uplink

NAV: network allocation vector

ACK: acknowledge

LGI: long guard interval

STF: short training field

LTF: long training field

SIG: signal field

RTS: request to send

L-SIG: non-HT signal field

L-STF: non-HT short training field

L-LTF: non-HT long training field

RL-SIG: repeated non-HT signal field

SIFS: short interframe space

TXOP: transmission opportunity

SS: simulation scenario

SLS: system level simulation

CF: contention free

CF-Poll: contention free poll

CF-END: contention free end

FIELD OF THE INVENTION

The present invention relates to the field of communicationstechnologies, and more specifically, to a method for transceiving in aWLAN and an apparatus.

BACKGROUND OF THE INVENTION

Wireless Local Area Networks (WLAN) is a data transmission system. Ituses radio frequency (RF) technology to replace the old twisted-paircopper wire formed by the local area network, making the wireless localarea network can use a simple access architecture allows users throughit, to achieve the purpose of information transmission. The developmentand application of WLAN technology has deeply changed people'scommunication way and working way, and brought people unprecedentedconvenience. With the wide application of intelligent terminals, thedemand for data network traffic is increasing day by day.

WLAN development is inseparable from the development and application ofits standards, including IEEE802.11 series is the main standard, thereare 802.11, 802.11b/g/a, 802.11n, 802.11ac. In addition to 802.11 and802.11b other standards are used Orthogonal Frequency DivisionMultiplexing, OFDM technology as the physical layer of the coretechnology.

SUMMARY OF THE INVENTION

In 802.11ax, the field of transmission opportunity (TXOP) duration wasincluded in HE-SIGA of SU PPDU, DL MU PPDU or UL MU PPDU, in order toreplace the Duration in MAC header in former standards. However thenumber of bit is still TBD.

The TXOP duration is the time remaining for a station (STA) to use achannel. For example, a STA sends a packet of lms, which is not countedin the remaining time of using the channel by the STA, because the 1 mshas already been used. TXOP duration indicates the remaining time duringwhich a channel is available for using by the station, such as 3 ms.There is a limit to the value of the remaining time.

Duration field in a MAC header has 16 bits (15 valid bits) in the unitsof 1 μs. It can indicate the maximum time duration of 32.767 ms.

In this application, we further discuss a solution which increases theefficiency of the indication of TXOP duration. In the method, thestation generates a PPDU, which carries a TXOP field (TXOP duration) inthe HE-SIGA of the PPDU, which is used for notifying the other stationof the remaining time of using the channel by the station, wherein theTXOP field can be indicated in different granularities (units). The PPDUis sent by the station. In a example, the TXOP field occupies 7 bitts,being indicated by two different granularities. For example, the twodifferent granularities include 8 μs and 256 μs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of indication of TXOP duration;

FIG. 2 illustrates the performance degradation of the opt1, 2, 3 andfixed 64 μs;

FIG. 3 illustrates an embodiment of indication of TXOP duration;

FIG. 4 illustrates an embodiment of indication of TXOP duration;

FIG. 5 illustrates an embodiment of indication of TXOP duration;

FIG. 6 illustrates an embodiment of indication of TXOP duration;

FIG. 7 illustrates an system of indication of TXOP duration;

FIG. 8 illustrates an apparatus of indication of TXOP duration.

DESCRIPTION OF EMBODIMENTS

TXOP limits in EDCA

AP can set the policy of channel access with the EDCA Parameter Setelement, where a TXOP limit is defined.

A TXOP limit has 16 bits in the unit of 32 μs. The default EDCAparameter of TXOP for each access category is as Table 1:

TABLE 1 TXOP limit For PHYs defined in Clause 18, For PHYs definedClause 19, in Clause 16 and Clause 20, and Other AC CWmin CWmax AIFSNClause 17 Clause 22 PHYs AC_BK aCWmin aCWmax 7 0 0 0 AC_BE aCWmin aCWmax3 0 0 0 AC_VI (aCWmin + 1)/2 − 1 aCWmin 2 6.016 ms 3.008 ms 0 AC_VO(aCWmin + 1)/4 − 1 (aCWmin + 1)/2 − 1 2 3.264 ms 1.504 ms 0

A STA can also be granted a TXOP with QoS data frames of subtypes thatinclude CF-Poll.

The time duration of the TXOP is carried in the 8-bit TXOP limitsubfield of QoS field in MAC header. The range of time values is 32 μsto 8160 μs.

There are also different regulations for TXOP in different countries,such as 4 ms in Japan.

It is provided that 4.08 ms-16.32 ms is a reasonable range for TXOPlimit for 802.11ax considering the efficiency and fairness amongdifferent BSS in the dense environment.

16.32 ms can support at least one pair of DL and UL PPDU in a cascadingstructure.

TXOP unit

The smaller TXOP unit cost large number of bits in HE-SIGA.

There are only 13or 14 bits in total left in the HE-SIGA of SU PPDU orDL MU PPDU.

Around 7˜9 bits can be used for TXOP duration considering the field ofspatial reuse and other potential new fields, e.g. non-contiguouschannel bonding.

3˜4 bits for SR.

2 bits for non contiguous channel bonding in DL MU PPDU.

The larger TXOP unit cost performance degradation due to NAV extensionat 3rd party STA.

As shown in FIG. 1 (SLS evaluation), we observed that the NAV extensionwill not exceed 2 times of the TXOP unit, no matter the length of TXOPand how many packet exchanged within the TXOP.

IEEE SS2 (can be seen in TGax simulation scenarios document(11-14-0980)), 32 BSSs; ˜64 STAs/BSS (totally 2048 STAs in 32 BSSs, thatis, about 64 STAs per BSS); Frequency Reuse factor=4;

20 MHz @5 GHz (in 5 GHz unlicensed band, the bandwidth is 20 MHz.);2T×2R, wherein the T is short for Transmission antenna number, the R isshort for Receiving antenna number.

Full buffer, 2 ms TXOP, RTS off

CF-END Off

TABLE 2 Unit (μs) Throughput (Mbps) Loss 1024 247.648 49.99% 512 331.48333.05% 256 394.352 20.36% 128 439.931 11.15% 64 466.632 5.76% 32 481.3092.80% 16 489.537 1.13% 1 (original) 495.153 0.00%

CF-END On

TABLE 3 unit (μs) Throughput (Mbps) Loss 1024 464.871 6.08% 512 466.1095.83% 256 465.743 5.91% 128 464.396 6.18% 64 465.582 5.94% 32 479.7363.08% 16 488.327 1.34% 1 (original) 494.983 0.00%

Considering the current numerology in 802.11ax, 4 μs˜32 μs is suitablefor the minimum TXOP unit.

Maximum symbol duration of 16 μs Data symbol+LGI.

Maximum symbol duration of 8 μs for HE-STF, 16 μs for HE-LTF+LGI.

32 μs fixed preamble overhead of 802.11ax.

PPDU(L-STF+L-LTF+L-SIG+RL-SIG+HE-SIGA)

Multi-level TXOP indication

Smaller TXOP unit for shorter TXOP, larger unit for longer TXOP, inorder to keep the similar relative loss.

E.g. 4 μs TXOP unit for TXOP length shorter than 128 μs, while 256 μsTXOP unit for TXOP length larger than 896 μs

The NAV extension can be alleviated by sending CF-end if the remainingtime is larger than 68 μs (CF-END+SIFS).

In this application, a method to indicate TXOP duration in HE-SIGA isdisclosed.

In order to achieve tradeoff between performance and overhead, 6 or 7bits are used with multi-level indication.

Example 1 (opt 1) shown in Table 4:

7 bits in total

2 bits indicate the TXOP unit: 4 μs/8 μs/16 μs/256 μs.

TABLE 4 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~124 μs 4 μs 0100000~11111 128 μs~376 μs 8 μs 10 00000~11111 384 μs~880 μs 16 μs  1100000~11111  896 μs~8832 μs 256 μs 

Example 2 (opt 2) shown in Table 5:

7 bits in total, wherein 2 bits indicate the TXOP unit: 8 μs/16 μs/32μs/512 μs.

TABLE 5 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~752 μs  16 μs 10 00000~11111 768 μs~1760 μs 32 μs 1100000~11111 1792 μs~17664 μs 512 μs 

Simplified solutions

Example 3 (opt 3), shown in Table 6:

6 bits in total, wherein 1 bit indicate the TXOP unit: 16 μs/512 μs.

TABLE 6 B1 B2~B6 TXOP range Unit 0 00000~11111 0 μs~496 μs 16 μs 100000~11111 512 μs~16384 μs 512 μs 

Comparison of the performance of the former three examples (opt):

Another example of 6 bits in total, shown in Table 7:

Wherein 2 bits indicate the TXOP unit: 8 μs/16 μs/32 μs/512 μs.

TABLE 7 B1B2 B3~B6 TXOP range Unit 00 0000~1111  0 μs~120 μs  8 μs 010000~1111 128 μs~368 μs 16 μs 10 0000~1111 384 μs~864 μs 32 μs 110000~1111  896 μs~8576 μs 512 μs 

Another example of 6 bits in total, shown in Table 8:

Wherein 2 bits indicate the TXOP unit: 16 μs/16 μs/32 μs/512 μs.

TABLE 8 B1B2 B3~B6 TXOP range Unit 00 0000~1111  0 μs~240 μs 16 μs 010000~1111 256 μs~496 μs 16 μs 10 0000~1111 512 μs~992 μs 32 μs 110000~1111 1024 μs~8704 μs 512 μs 

Another example of 6 bits in total, shown in Table 9:

Wherein 2 bits indicate the TXOP unit: 16 μs/16 μs/16 μs/512 μs.

TABLE 9 B1B2 B3~B6 TXOP range Unit 00 0000~1111  0 μs~240 μs 16 μs 010000~1111 256 μs~496 μs 16 μs 10 0000~1111 512 μs~752 μs 16 μs 110000~1111  768 μs~8448 μs 512 μs 

Example 4, shown in Table 10:

Fixed 64 μs granularity with 7 bit in total.

TABLE 10 B1~B7 TXOP range Unit 0000000~1111111 0 μs~8128 μs 64 μs

Example 5, shown in Table 11:

7 bits in total

2 bits indicate the TXOP unit: 4 μs/16 μs/64 μs/256 μs.

TABLE 11 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~124 μs  4 μs 0100000~11111 128 μs~624 μs  16 μs 10 00000~11111 640 μs~2624 μs 64 μs 1100000~11111 2688 μs~10624 μs 256 μs 

Example 6, shown in Table 12:

7 bits in total

2 bits indicate the TXOP unit: 8 μs/16 μs/32 μs/256 μs

TABLE 12 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~752 μs 16 μs 10 00000~11111  768 μs~1760 μs 32 μs 1100000~11111 1792 μs~9728 μs 256 μs 

Example 7, shown in Table 13:

7 bits in total

2 bits indicate the TXOP unit: 8 μs/16 μs/64 μs/256 μs

TABLE 13 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~752 μs  16 μs 10 00000~11111 768 μs~2752 μs 64 μs 1100000~11111 2816 μs~10752 μs 256 μs 

Example 8, shown in Table 14:

7 bits in total

2 bits indicate the TXOP unit: 8 μs/16 μs/64 μs/512 μs

TABLE 14 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~752 μs  16 μs 10 00000~11111 768 μs~2752 μs 64 μs 1100000~11111 2816 μs~18688 μs 512 μs 

Example 9, shown in Table 15:

7 bits in total

2 bits indicate the TXOP unit: 8 μs/32 μs/128 μs/512 μs.

TABLE 15 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~1248 μs  32 μs 10 00000~11111 1280 μs~5248 μs  128 μs11 00000~11111 5376 μs~21248 μs 512 μs

Example 10, shown in Table 16:

7 bits in total

2 bits indicate the TXOP unit: 8 μs/32 μs/64 μs/512 μs

TABLE 16 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs  8 μs 0100000~11111 256 μs~1248 μs 32 μs 10 00000~11111 1280 μs~3264 μs  64 μs11 00000~11111 3328 μs~19200 μs 512 μs 

Example 11, shown in Table 17

7 bits in total

2 bits indicate the TXOP unit: 8 μs/8 μs/8 μs/256 μs

TABLE 17 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs 8 μs 0100000~11111 256 μs~504 μs 8 μs 10 00000~11111 512 μs~760 μs 8 μs 1100000~11111  768 μs~8704 μs 256 μs 

TXOP duration for ACK/BA/MBA

The TXOP duration field in HE-SIGA can also indicate the time durationfor the ACK/BA/MBA immediately following the data PPDU. Shown in FIG. 3.

We can use 7 bits to indicate lms with the unit of 8 μs, which can covermost of the ACK/BA/MBA frames with low MCS.

TABLE 18 B1~B7 TXOP range Unit 0000000~1111111 0 μs~1016 μs 8 μs

Or, in another example,

TABLE 19 B1~B7 TXOP range Unit 0000000~1111111 0 μs~2032 μs 16 μs

Example 12

As shown in Table 20, example 12 is has been disclosed by example 11,which excludes the entry 11111 in Table 17. TXOP in HE-SIGA can use 7bits with 2 granularities, one is small and one is large granularity.For example, small granularity uses 8 μs to indicate the TXOP range from0˜760 μs with 96 entries, and large granularity uses 256 μs to indicatethe TXOP range from 768˜8448 μs with 31 entries. 2 bits indicate theTXOP unit: 8 μs/8 μs/8 μs/256 μs

TABLE 20 B1B2 B3~B7 TXOP range Unit 00 00000~11111  0 μs~248 μs 8 μs 0100000~11111 256 μs~504 μs 8 μs 10 00000~11111 512 μs~760 μs 8 μs 1100000~11110  768 μs~8448 μs 256 μs 

As the duration field in MAC header is in lus unit, there will beaccuracy difference between duration in MAC header and TXOP in HE-SIGA.To avoid the over-protection issue that TXOP in HE-SIGA is large thanduration in MAC header, the valid duration information indicated by theTXOP field in HE-SIGA shall be the largest feasible duration informationthat is smaller than or equal to the duration information indicated bythe Duration field in a MAC header in the HE PPDU. Then TXOP in HE-SIGAis always less than the exact duration in MAC header with a delta_T,shown in FIG. 4, which relies on the granularity used. This cause aunder-protection issue that TXOP in HE-SIGA can't cover the exactduration in MAC header.

To avoid the under-protection issue, we add the following rules:

-   (1)Assuming TXOP holder sends a soliciting frame(e.g. frame 0) with    TXOP in HE-SIGA to be the value PHT_0. TXOP responder should    transmit a responding frame(e.g. frame 1) no longer than    PHT_0-SIFS_time, to avoid that the reception of responding frame at    TXOP holder is interfered by OBSS STA which only decodes TXOP field    in soliciting frame from TXOP holder and set NAV with PHT_0. Show in    FIG. 5.-   (2)Assuming TXOP holder receives a responding frame from TXOP    responder with TXOP in HE-SIGA to be the value PHT_1. If TXOP holder    transmits to the same TXOP responder, it should transmit another    soliciting frame(e.g. frame 2) no longer than PHT_1-SIFS_time, to    avoid that the reception of the soliciting frame(frame 2) at TXOP    responder is interfered by OBSS STA which only decodes TXOP field in    responding frame from TXOP responder and set NAV with PHT1. Shown in    FIG. 6.-   Note: These two rules apply to all example for TXOP encoding tables    above.

The scheme of the embodiments is applicable to a WLAN network system.The following is a schematic diagram of an applicable scenario of themethod in a wireless local area network provided by embodiments. Asshown in FIG. 7 below, the WLAN network system may include an accessstation 101 and at least a station 102. In the WLAN network system, somestations (non-AP station or AP) may work as a TXOP holder, others maywork as a responder, like shown in FIG. 4, 5, or 6.

An access point (AP, Access Point) may also be referred to as a wirelessaccess point, a bridge, a hotspot, or the like, and may be an accessserver or a communications network.

A station (STA, Station) may be further referred to as a user, and maybe a wireless sensor, a wireless communications terminal, or a mobileterminal, for example, a mobile telephone (or referred to as a“cellular” phone) that supports a WiFi communication function and acomputer that has a wireless communication function. For example, thestation may be a portable, pocket-sized, handheld, computer built-in,wearable, or in-vehicle wireless communications apparatus that supportsthe WiFi communication function, and exchanges communication data suchas voice and data with a wireless access network.

A person skilled in the art knows, some communication equipment mayinclude the both functions of the above STA and AP. It's not limited inthe embodiments.

FIG. 8 is a schematic diagram of a data transmission apparatus (such asan access point, a station, a chip, or the like) provided in theembodiment s. As shown in FIG. 8 below, the data transfer apparatus 1200may be implemented as general bus architecture for the bus 1201.Depending on the particular application of the data transfer apparatus1200 and the overall design constraints, the bus 1201 may include anynumber of interconnect buses and bridges. The bus 1201 couples variouscircuits, including a processor 1202, storage medium 1203, and a businterface 1204. The bus 1201, the data transfer apparatus 1200 uses thebus interface 1204 to connect the network adapter 1205 and the like viathe bus 1201. As shown in FIG. The network adapter 1205 may be used toimplement the signal processing functions of the physical layer in thewireless local area network and transmit and receive the radio frequencysignals via the antenna 1207. The user interface 1206 may connect a userterminal, such as a keyboard, a display, a mouse, a joystick, or thelike. The bus 1201 may also be connected to various other circuits suchas timing sources, peripherals, voltage regulators, power managementcircuits, etc., which are well known in the art and will not bedescribed in detail.

The data transfer apparatus 1200 may also be configured as a generalprocessing system that includes one or more microprocessors that provideprocessor functionality, and an external memory that provides at least aportion of the storage medium 1203, all of which are communicated via anexternal bus system The structure is connected with other supportingcircuits.

Alternatively, the data transfer apparatus 1200 may be implemented usingan ASIC (application-specific integrated circuit) having a processor1202, a bus interface 1204, a user interface 1206, and at least aportion of a storage medium 1203 integrated in a single chip, or, Thedata transmission device 1200 may be implemented using one or more of anFPGA (Field Programmable Gate Array), a PLD (Programmable Logic Device),a controller, a state machine, gate logic, discrete hardware components,any other suitable Circuits, or any combination of circuits capable ofperforming the various functions described throughout this disclosure.

The processor 1202 is responsible for managing the bus and generalprocessing (including executing the software stored on the storagemedium 1203). The processor 1202 may be implemented using one or moregeneral purpose processors and/or dedicated processors. Examples ofprocessors include microprocessors, microcontrollers, DSP processors,and other circuits capable of executing software. Software should bebroadly construed to mean instructions, data, or any combinationthereof, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. The storagemedium 1203 is shown as being separate from the processor 1202, however,it will be readily apparent to those skilled in the art that the storagemedium 1203 or any portion thereof may be located outside of the datatransmission device 1200. For example, the storage medium 1203 mayinclude a transmission line, a carrier waveform modulated with data,and/or a computer article separated from the wireless node, all of whichmay be accessed by the processor 1202 via the bus interface 1204.Alternatively, the storage medium 1203 or any portion thereof may beintegrated into the processor 1202, which may be, for example, a cacheand/or general purpose register.

The processor 1202 may perform the above-described embodiments, and willnot be described herein.

It will be appreciated by those of ordinary skill in the art that all orpart of the steps of implementing the method embodiments described abovemay be accomplished by program related hardware which may be stored in acomputer-readable storage medium which, when executed, including thesteps of the above-described method embodiment, and the aforementionedstorage medium includes various kinds of media, such as a ROM, a RAM, amagnetic disk, or an optical disk, on which program codes can be stored.

The embodiments can be applied to wireless local area networks,including, but not limited to, Wi-Fi systems represented by 802.11a,802.11b, 802.11g, 802.11n, and 802.11ac and also to next-generationWi-Fi systems, Wireless LAN systems.

Of course, it may be applied to other possible wireless networks.

The following provides a number of embodiments provided by a simplelanguage description:

An information transmission method for radio communication,

Generating, by a sending site, a PPDU carrying a TXOP field in theHE-SIGA of the PPDU, the TXOP field is used for notifying the otherstations of the remaining time of the station usage channel, wherein theTXOP field can be indicated by different granularity;

sending the PPDU.

An information receiving method for radio communication,

receiving, a PPDU sent by a sending site, the HEOPA of the PPDU carryinga TXOP field for informing other stations of the remaining time of thestation usage channel, wherein the TXOP field may be carried out atdifferent granularity Instructions;

sending, a TXOP response frame according to the received PPDU.

The method according to embodiment 1 or 2, the TXOP field is indicatedusing two different granularity.

The method of embodiment 3, the TXOP field is indicated by twogranularities of 8 μs and 256 μs.

The method of embodiment 4, wherein the TXOP field is 7 bits in lengthand includes 128 values; wherein 96 values are indicated by agranularity of 8 μs, the indicated TXOP range is 0 to 760 microseconds;31 The number is indicated with a granularity of 256 μs and theindicated TXOP range is 768 to 8448 μs.

The method according to embodiment 2, further comprising:

the TXOP length of the TXOP response frame should be less than or equalto the length remaining after subtracting the SIFS time from the valuerepresented by the TXOP field in the initiation frame of the station(TXOP origination station).

The method of embodiment 1, wherein the station sends a new TXOPinitiation frame if the destination address of the new TXOP transmitframe matches the transmit address of the station that sent the previousTXOP response frame, the new TXOP transmission frame should be less thanor equal to the length remaining after the SIFS time minus the valuerepresented by the TXOP field in the TXOP response frame.

The method of embodiment 2, after receiving a PPDU sent by the sendingsite, replies to an ACK or BA, the ACK or BA comprising a duration fieldin the granularity representation, the duration field being representedby The time at which the other stations will be notified of the channelto be used.

A communication device comprising a memory and a processor, operable toperform methods such as 1, 3-5, 7.

A communication device comprising a memory and a processor, operable toperform methods such as 2, 3-5, 8.

1. A method for indicating a transmission opportunity (TXOP) duration ina wireless communication system, comprising: generating, by a TXOPholder, a physical layer protocol data unit (PPDU), wherein the PPDUincludes a High Efficiency Signal field A (HE-SIGA), the HE-SIGAincludes a TXOP duration field, the TXOP duration field is used toindicate to other stations a remaining time for using a channel by astation, and the TXOP duration field includes a first part whichindicates a granularity used, and a second part which indicates the TXOPduration using the granularity indicated by the first part; and sending,by the TXOP holder, the generated PPDU.
 2. The method according to theclaim 1, wherein the granularity indicated by the first part of the TXOPduration field is from a group of at least two granularities, and thegroup of at least two granularities is used to indicate different TXOPdurations in the wireless communication system.
 3. The method accordingto the claim 2, wherein the group of at least two granularities includesa granularity of 8 μs.
 4. The method according to the claim 1, whereinthe TXOP duration field has 7 bits in total.
 5. The method according tothe claim 1, wherein the first part of the TXOP duration field has 1 or2 bits.
 6. A method for indicating a transmission opportunity (TXOP)duration in a wireless communication system, comprising: receiving, by aTXOP responder, a physical layer protocol data unit (PPDU), wherein thePPDU includes a High Efficiency Signal field A (HE-SIGA), the HE-SIGAincludes a TXOP duration field, the TXOP duration field is used toindicate to other stations a remaining time for using a channel by astation, and the TXOP duration field includes a first part whichindicates a granularity used, and a second part which indicates the TXOPduration using the granularity indicated by the first part; and sending,by the TXOP responder, a responding frame in response to the receivedPPDU.
 7. The method according to the claim 6, wherein the granularityindicated by the first part of the TXOP duration field is from a groupof at least two granularities, and the group of at least twogranularities is used to indicate different TXOP durations in thewireless communication system.
 8. The method according to the claim 7,wherein the group of at least two granularities includes a granularityof 8 μs.
 9. The method according to the claim 6, wherein the TXOPduration field has is 7 bits in total.
 10. The method according to theclaim 6, wherein the first part of the TXOP duration field has 1 or 2bits.
 11. A communication apparatus comprising at least one processor;and a non-transitory computer-readable storage medium coupled to the atleast one processor and storing programming instructions for executionby the at least one processor, the programming instructions instruct theat least one processor to: generate a physical layer protocol data unit(PPDU), wherein the PPDU includes a High Efficiency Signal field A(HE-SIGA), the HE-SIGA includes a transmission opportunity (TXOP)duration field, the TXOP duration field is used to indicate to otherstations a remaining time for using a channel by a station, and the TXOPduration field includes a first part which indicates a granularity used,and a second part which indicates a TXOP duration using the granularityindicated by the first part; and send the generated PPDU.
 12. Theapparatus according to the claim 11, wherein the granularity indicatedby the first part of the TXOP duration field is from a group of at leasttwo granularities, and the group of at least two granularities is usedto indicate different TXOP durations in a wireless communication system.13. The apparatus according to the claim 12, wherein the group of atleast two granularities includes a granularity of 8 μs.
 14. Theapparatus according to the claim 11, wherein the TXOP duration field has7 bits in total.
 15. The apparatus according to the claim 11, whereinthe first part of the TXOP duration field has 1 or 2 bits.
 16. Acommunication apparatus comprising at least one processor; and anon-transitory computer-readable storage medium coupled to the at leastone processor and storing programming instructions for execution by theat least one processor, the programming instructions instruct the atleast one processor to: receive a physical layer protocol data unit(PPDU), wherein the PPDU includes a High Efficiency Signal field A(HE-SIGA), the HE-SIGA includes a transmission opportunity (TXOP)duration field, the TXOP duration field is used to indicate to otherstations a remaining time for using a channel by a station, and the TXOPduration field includes a first part which indicates a granularity used,and a second part which indicates a TXOP duration using the granularityindicated by the first part; and send a responding frame in response tothe received PPDU.
 17. The apparatus according to the claim 16, whereinthe granularity indicated by the first part of the TXOP duration fieldis from a group of at least two granularities, and the group of at leasttwo granularities is used to indicate different TXOP durations in awireless communication system.
 18. The apparatus according to the claim17, wherein the group of at least two granularities includes agranularity of 8 μs.
 19. The apparatus according to the claim 16,wherein the TXOP duration field has 7 bits in total.
 20. The apparatusaccording to the claim 16, wherein the first part of the TXOP durationfield has 1 or 2 bits.